Combined receiver and microphone



Mmh 24, 1931.

'F. c. YOUNG COMBINED RECEIVER AND MICROPHONE Filed Oct. 17, 1928 2 Sheets-Sheet l \NVENTOR BY QREDERK: YOUNG March 24, 1931. F. c. YOUNG 1,797,391

COMBINED RECEIVER AND MICROPHONE Filed 001;. 17, 1928 2 Sheets-Sheet 2 INVENTOR BY FREDERIC 0 YOUNG &

ATTOR Y Patented Ma. 24, 1931 FREDERIG o. YOUNG, or RocHEs'rEE; NEW YORK, ASSIGNOR mo THE sTRoMBERG- :CARLSON TELErHonE-MAnUEAcrnnme COMPANY, OF ROCHESTER, NEW YORK, A

j CORPORATION OF NEVJ YORK COMBINED BEcErvEElAnn rcEornoNE- Application filed October 17,1923; Seria1 No. 313,013."

This invention relates" to *a "combined re "ceiver and microphone known in the art as stand set: W V Combinedreceivers and transmitters or hand sets have long been'recognized as a lkzonvenient -i 'o"r1rrof telephone instrument but v.they have not come intdextensive use beg cement the factthat there wasg'ate'ndency for howling due to interaction "betweenf the receiver and microph ne. In addition, "the transmission, through such "types "of telephonein'strunients has'not been up to the.

standardof thewell-known desk set since the sound waves were inefiiciently applied to the 15 mic'rophone.

L: In accordance with the present invention a handset has been designed which practically eliminates all howling or interaction and which greatly improves speech transmission. The deficient speech transmission of former Combined receivers and microphones was due toflthe' fact that in order to provide a hand set that was compact and convenient for use it was necessary to have the microphonediaapplied to-the ear of theuserthe voice waves weren'ot transmitted directlyagainst the dia phragm but were-propagated at an "angleof about 20 degrees to the plane; thereof. Funnel-shaped mouthpieces have been" used to direct speech against the diaphragm,,but such a design has failed to take into c0'nsid'eration the fact "that substantially all f of the voice waves which strike the transmitter diaphragm under these conditionsimust' be refiectedwaves. These mouthpieces have use *allyideveloped interference between the "various reflected sound waves so that the "ef ficiency thereof was greatly reduced. g

One of the features ofythe'present inventhe sound waves represented by the parallel V microphone, so that the voice waves are efiiciently reflected toward-the properqportion I olfthe microphone diaphragm when the re,

ceiver is applied tothe ear of the telephone,

7 user. Other features will appear. from the detailed description and from theclaimsli. I a v phragm substantially parallel'td the"plan'e of thereceiver so that when the, receiver was perspective view andFigure'2 is a side view with portions broken away, showing thecon- 'struction ofthem'outhpiece of a combined receiver and microphone or hand set. Figures 3 and-4 represent a cross sectional View anda perspective view respectively of a dif- :ferent form of mouthpiece for' use instead of the mouthpiece shown-in Figures 1 and 2 Refe ring tOi the form of the invention shown 11']. Figures 1 and 2, 5 designates a handle of proper contourto be easily grasped and held by the user. At the upper end of this handle there is secured a flat receiver angles'to the main portion of the handle,

in which there is mounted a microphone or transmitter having a diaphragm 8 indicated by a heavy. dotted line. The diaphragm of [the transmitter is in a plane substantially "parallel to but-atthe right of the plane of thereceiver diaphragm as shown in Figure 2 so that the receiver 6 and transmitter may" be properly positioned for listening and talk- 13 which is provided with suitable lugs to screwed onto the extension 7. The mouthpiece SJhas an inner surface 11 substantially V parallel with'the transmitter diaphragm and an extension 9, the inner surface 10 of which ls a planey The surface 11 has a series of elongated openings 12 therein of such length "and'so positioned that they are adjacent a predetermined area near the center of the transmitter diaphragm. The flat surface 10 defines such an angle with the surface 11 that trated on an area near the center of the diaing. The transmitterand-its diaphragm are a covered bymouthpiece generally designated pieces have been used but in these the reflecting surfacewas such thatmany of the waves "Referring to the'drawings, Figure instead of being reflected against the'transmitter diaphragm were dissipated against the interior of the mouthpiece and even those that were reflected against the transmitter were inefficiently used. 7 Even in the cylindrical type of mouthpiece the sound waves were reflected at various angles and struck the diaphragm at different angles and in addition had unequal concentration upon the effective surface of the diaphragm. Furthermore, the lengths of the paths of the different reflected waves were not equal and therefore the waves arrived at the diaphragm out of phase with each other especially at frequencies above approximately 1000 cycles. It will be recognized that this materially reduced the efliciency since one wave frequently tended to neutralize another. However, where a plane reflecting surface such as shown in Figures land 2 is used certain of these diflicultieshave been removedsince substantially all of the sound waves are reflected through the same angle and these waves impinge upon the diaphragm in such a manner that all of the angles of incidenceare-equal.

In addition to these reflected sound waves, certain of the direct waves strike the diaphragm as indicated by the three left hand rays of the group designated 12 in Figure 2. In this arrangement, since the slots 12 are properly positioned, there is a uniform: distribution of thereflected'soundwaves over the used part of the diaphragm with a resulting improvement in efficiency.

In the arrangement shown in Figures-3 and i there is. disclosed an'arrangement for efliciently applying reflected sound waves to the diaphragm of the transmitter. It willbe understood that the mouthpiece. shown in these figures may be substituted for that shown in Figures 1 and 2 This mouthpiece includes a cup-shaped molded structure. generally designated15 which maybe attached to the extension 7 of the'handle of Figure 2 by any suitable means although a ring engaging shoulder 16 on the mouthpiece may be provided with screw threads to engage similar threads on the extension 7. The inner surface 18 of the mouthpiece is defined by a paraboloid. of revolution with its axis parallel to rays 12 representing sound waves and with its focal point at the openin'g 19 in the portion of the mouthpiece adjacent the diaphragm of the microphone. This opening 19 is near the center of the diaphragm so that sound waves reflected therethrough strike its most sensitive portion. The mouthpiece also has a series of openings 20 uniformly spaced surrounding the opening 19 for a purpose to be described. -With this mouthpiece sound waves represented by the parallel lines 21 strike the surface 18 and are reflected in such a; manner that they strike the center of the diaphragm. It will be noted that the lengths of all these paths from the source of sound to the diaphragmis the same Which meansthat opening and saiddiaphragm.

. the transmitter diaphragm.

What I claim is 1. A mouthpiece for a combined receiver and transmitter having aplurality of openings uniformly spaced in a plane-adjacent a predetermined area of a transmitter diaphragm and having a reflecting surface ill-2 tersec-ting said plane such that sound waves .entering the mouthpiecepass through said openings with substantially no refleetionof any sound wavesoutside of the mouthpiece.

2. A mouthpiece for a combined receiver and transmitter mounted adjacent the diaphragm of said transmitter, said mouthpiece having a central opening and a plurality of uniformly spaced openings leading to said diaphragm, said mouthpiece having a surface defined by a-portion of a paraboloid of revolutionfor reflecting sound waves through said first opening, said surrounding openings .serving to pass direct sound waves to said transmitter diaphragm.

3. A mouthpiece for a combined receiver and transmitter mounted adjacent the diaphragm of said transmitter, said mouthpiece having an opening to said diaphragm and a surface defined by a portion of a paraboloid of revolution for reflecting sound waves through said opening,- said paraboloid of revolution having one of its foci adjacent said 4. In a combined receiver and transmitter a handle having a receiver with its flat surface mounted on and parallel to the long axis of said handle, a transmitter including a diaphragm mounted on said handle in spaced relation to said receiver, said transmitter being mounted in a plane substantially parallel to but at a greater distance from said handle than said receiver, and a mouthpiece for saidtransmitter having an opening therein adjacent said diaphragm and having a surface defined by a portion of a rparaboloid of revolution for reflecting sound waves into said opening, said paraboloid of revolution having one of its'foci adja'cent said opening. V

5. A mouthpiece for a combined receiver and transmitter mounted adjacent the dis.-

phra-gm of said transmitter, said mouthpiece having an opening leading to said diaphragm 7 and having a reflecting surface defined by 9.

portion-0f a paraboloid of revolution whose axis is parallelto the normal direction'of ifnovement of sound waves against said surace.

6. A mouthpiece for a transmitter provided, with a diaphragm, said mouthpiece having a perforated portion substantially parallel to said diaphragm and a second portion joined to said perforated portion at an angle thereto for reflecting through said perforated portion substantially all of the sound Waves striking said second portion.

In witness whereof,-I hereunto subscribe my name this 8th day of October, A. D. 1928.

FREDERIC C. YOUNG. 

